An automatic machine for processing tobacco articles —e.g. a cigarette manufacturing machine, filter assembly machine, packing machine, or cellophaning machine—comprises a substantially parallelepiped-shaped supporting frame having a vertical front wall, a vertical rear wall, two vertical lateral walls, a horizontal top wall, and a horizontal bottom wall. Substantially all the operating devices of the machine (conveyors, feed devices, folding devices, gumming devices, etc.) are located at the front wall which was formerly left clear to permit fast, easy access to all the operating devices of the machine, while the other (lateral, top, bottom, and rear) walls of the frame were normally closed by removable sheet metal panels. Recent international regulations for safeguarding the health and safety of automatic machine operators, however, require mechanical barriers to prevent accidental contact with moving parts, and establish maximum machine noise levels within the workplace.
Following the entry into force of the above regulations, automatic machines for processing tobacco articles have each been equipped with a casing covering and completely enclosing the front, and which is defined by a fixed supporting structure supporting a number of rigid soundproofing panels, at least some of which are fitted to the supporting structure so as to be movable easily, when the automatic machine is off, from a closed position to an open position enabling access to the operating parts of the machine. One example of an automatic tobacco article processing machine equipped with a casing of the above type is described in Patents U.S. Pat. Nos. 4,619,277A1, 3,866,708A1 and 4,671,299A1, and others in Patents U.S. Pat. Nos. 3,851,725A1, 3,860,086A1, 3,961,874A1, 4,509,442A1 and EP0737620A1.
To further reduce the maximum noise level of automatic tobacco article processing machines within the workplace, it has also been proposed to fit the sheet metal panels closing the lateral, top, bottom and rear walls of the frame with a layer of soundproofing machine, as described in Patent Application EP1082915A1.
GB-1442751-A discloses a cigarette making machine provided with a sound proof L-shaped enclosure having at least one air inlet and at least one outlet; a suction device is provided within the enclosure to cause air circulation. Air enters through an opening located above a filter attachment device in one limb of the L and more air enters through an inlet in the other limb; a fan draws air from the machine bed and thrusts to an outlet. Air is also driven to the outlet by a fan which also operates the various suction devices of the filter attachment device.
Tests have shown the above solutions to be normally capable of reducing the noise level of currently used automatic tobacco article processing machines within the workplace to a maximum of 84 to 88 dB. Certain situations, however, call for a maximum noise level of 79 dB. Moreover, given the continual increase in operating speed (at present, the equivalent of processing 20,000 cigarettes a minute), modern automatic machines tend to make more noise, so that producing a modern automatic machine with a maximum noise level of 79 dB using the above known noise abatement solutions is extremely complicated and expensive.
EP-1422145-A1 discloses a volume element which completely encloses a cigarettes production line so that the inside can be kept temperate; in particular, different areas inside the volume element can be kept at different temperatures. A sensor can be provided to measure air humidity, pressure and/or temperature inside the volume element.